mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
synced 2024-11-23 02:01:12 +00:00
docs: Gram and nit fixes for part-bufferpool.txt
This commit is contained in:
parent
06a79347f3
commit
20c32ffbdf
1 changed files with 16 additions and 16 deletions
|
@ -4,7 +4,7 @@ Bufferpool
|
|||
This document details the design of how buffers are be allocated and
|
||||
managed in pools.
|
||||
|
||||
Bufferpools increases performance by reducing allocation overhead and
|
||||
Bufferpools increase performance by reducing allocation overhead and
|
||||
improving possibilities to implement zero-copy memory transfer.
|
||||
|
||||
Together with the ALLOCATION query, elements can negotiate allocation properties
|
||||
|
@ -40,7 +40,7 @@ GstBufferPool
|
|||
The bufferpool object manages a list of buffers with the same properties such
|
||||
as size, padding and alignment.
|
||||
|
||||
The bufferpool has two states: active and inactive. In the in-active
|
||||
The bufferpool has two states: active and inactive. In the inactive
|
||||
state, the bufferpool can be configured with the required allocation
|
||||
preferences. In the active state, buffers can be retrieved from and
|
||||
returned to the pool.
|
||||
|
@ -99,13 +99,13 @@ Allocation query
|
|||
guint max_buffers;
|
||||
}
|
||||
|
||||
use gst_query_parse_nth_allocation_pool() to get the values.
|
||||
Use gst_query_parse_nth_allocation_pool() to get the values.
|
||||
|
||||
The allocator can contain multiple pool configurations. If need-pool
|
||||
was TRUE, the pool member might contain a GstBufferPool when the
|
||||
downstream element can provide one.
|
||||
|
||||
Size contains the size of the bufferpool buffers and is never 0.
|
||||
Size contains the size of the bufferpool's buffers and is never 0.
|
||||
|
||||
min_buffers and max_buffers contain the suggested min and max amount of
|
||||
buffers that should be managed by the pool.
|
||||
|
@ -125,7 +125,7 @@ Allocation query
|
|||
GstAllocationParams params;
|
||||
}
|
||||
|
||||
use gst_query_parse_nth_allocation_param() to get the values
|
||||
Use gst_query_parse_nth_allocation_param() to get the values.
|
||||
|
||||
The element performing the query can use the allocators and its
|
||||
parameters to allocate memory for the downstream element.
|
||||
|
@ -144,7 +144,7 @@ Allocation query
|
|||
|
||||
These metadata items can be accepted by the downstream element when
|
||||
placed on buffers. There is also an arbitrary GstStructure associated
|
||||
with the metadata that contains metadata specific options.
|
||||
with the metadata that contains metadata-specific options.
|
||||
|
||||
Some bufferpools have options to enable metadata on the buffers
|
||||
allocated by the pool.
|
||||
|
@ -214,7 +214,7 @@ of a caps change), alignment or number of buffers.
|
|||
RECONFIGURE event upstream. This instructs upstream to renegotiate both
|
||||
the format and the bufferpool when needed.
|
||||
|
||||
A pipeline reconfiguration is when new elements are added or removed from
|
||||
A pipeline reconfiguration happens when new elements are added or removed from
|
||||
the pipeline or when the topology of the pipeline changes. Pipeline
|
||||
reconfiguration also triggers possible renegotiation of the bufferpool and
|
||||
caps.
|
||||
|
@ -293,13 +293,13 @@ Use cases
|
|||
those elements require more than that amount of buffers for temporary
|
||||
storage.
|
||||
|
||||
The bufferpool of myvideosink will then be configured with the size of the
|
||||
Myvideosink's bufferpool will then be configured with the size of the
|
||||
buffers for the negotiated format and according to the padding and alignment
|
||||
rules. When videotestsrc sets the pool to active, the 3 video
|
||||
buffers will be preallocated in the pool.
|
||||
|
||||
videotestsrc acquires a buffer from the configured pool on its srcpad and
|
||||
pushes this into the queue. When the videotestsrc has acquired and pushed
|
||||
pushes this into the queue. When videotestsrc has acquired and pushed
|
||||
3 frames, the next call to gst_buffer_pool_acquire_buffer() will block
|
||||
(assuming the GST_BUFFER_POOL_FLAG_DONTWAIT is not specified).
|
||||
|
||||
|
@ -324,9 +324,9 @@ Use cases
|
|||
decoder linked to a fakesink but we will then dynamically change the
|
||||
sink to one that can provide a bufferpool.
|
||||
|
||||
When it negotiates the size with the downstream element fakesink, it will
|
||||
When myvideodecoder negotiates the size with the downstream fakesink element, it will
|
||||
receive a NULL bufferpool because fakesink does not provide a bufferpool.
|
||||
It will then select its own custom bufferpool to start the datatransfer.
|
||||
It will then select its own custom bufferpool to start the data transfer.
|
||||
|
||||
At some point we block the queue srcpad, unlink the queue from the
|
||||
fakesink, link a new sink and set the new sink to the PLAYING state.
|
||||
|
@ -334,7 +334,7 @@ Use cases
|
|||
and, through queue, inform myvideodecoder that it should renegotiate its
|
||||
bufferpool because downstream has been reconfigured.
|
||||
|
||||
Before pushing the next buffer, myvideodecoder would renegotiate a new
|
||||
Before pushing the next buffer, myvideodecoder has to renegotiate a new
|
||||
bufferpool. To do this, it performs the usual bufferpool negotiation
|
||||
algorithm. If it can obtain and configure a new bufferpool from downstream,
|
||||
it sets its own (old) pool to inactive and unrefs it. This will eventually
|
||||
|
@ -348,13 +348,13 @@ Use cases
|
|||
|
||||
myvideodecoder has negotiated a bufferpool with the downstream myvideosink
|
||||
to handle buffers of size 320x240. It has now detected a change in the
|
||||
video format and need to renegotiate to a resolution of 640x480. This
|
||||
requires it to negotiate a new bufferpool with a larger buffersize.
|
||||
video format and needs to renegotiate to a resolution of 640x480. This
|
||||
requires it to negotiate a new bufferpool with a larger buffer size.
|
||||
|
||||
When myvideodecoder needs to get the bigger buffer, it starts the
|
||||
negotiation of a new bufferpool. It queries a bufferpool from downstream,
|
||||
reconfigures it with the new configuration (which includes the bigger buffer
|
||||
size) and it then sets the bufferpool to active. The old pool is inactivated
|
||||
size) and sets the bufferpool to active. The old pool is inactivated
|
||||
and unreffed, which causes the old format to drain.
|
||||
|
||||
It then uses the new bufferpool for allocating new buffers of the new
|
||||
|
@ -371,7 +371,7 @@ Use cases
|
|||
change the resolution.
|
||||
|
||||
myvideosink sends a RECONFIGURE event upstream to notify upstream that a
|
||||
new format is desirable. upstream elements try to negotiate a new format
|
||||
new format is desirable. Upstream elements try to negotiate a new format
|
||||
and bufferpool before pushing out a new buffer. The old bufferpools are
|
||||
drained in the regular way.
|
||||
|
||||
|
|
Loading…
Reference in a new issue